The current invention is generally related to image formation or reproduction, and more particularly related to the image formation on an image-carrying medium using an image-forming material whose adhesion force is sensitive to a predetermined stimulus.
Japanese Patent Publications Hei 10-798, 10-76689, 10-81028 and 10-157175 all have disclosed thermal image-forming devices. In stead of a photoreceptor used in an electrostatic process, the thermal image-forming devices in general include an image-forming surface whose adhesion force changes based upon temperature, a heating unit for selectively heating the image-forming surface, a application unit for applying colorant to the image-forming surface and a transferring unit for transferring the colorant from the image-forming surface. The above described thermal image forming device do not perform complex image formation processes as required in electrostatic devices and also advantageously do not produce harmful material such as image ozone.
According to the above Japanese Patent Publications, the prior art thermal devices are not able to produce a sharp image. The image formation by colorant on an image-forming surface is relative stable since the colorant is placed on the image-forming surface due to adhesion force. However, when the colorant is transferred from the image-forming surface to an image-carrying medium, since the voltage or electrostatic transfer method is used, the conventional problem of the colorant dispersion is not solved. The prior art thermal image formation devices fail to output a high-resolution image.
To solve the above described problem, it is desired to substantially minimize the dispersion of colorant when the colorant or developer is transferred from the image-forming surface onto an image-carrying medium. It is also desired to eliminate the generation of ozone during the image formation process while the image is formed in a high resolution.
In order to solve the above and other problems, according to a first aspect of the current invention, a method of controlling relative adhesion force of predetermined developer and an image-forming surface with respect to a predetermined image-carrying medium, includes the acts of adjusting a first adhesion force level of the predetermined developer; adjusting a second adhesion force level of the image-forming surface; placing the predetermined developer on the image-forming surface according to a desired image when the second adhesion force level is higher than the first adhesion force level; and transferring the predetermined developer on the image-forming surface onto the image-carrying medium when the first adhesion force level is higher than the second adhesion force level.
According to a second aspect of the current invention, a method of controlling relative adhesion force of predetermined developer and an image-forming surface with respect to a predetermined image-carrying medium, including acts of adjusting a first adhesion force level of the predetermined developer; adjusting a second adhesion force level of the image-forming surface; placing the predetermined developer on the image-forming surface according to a desired image when the first adhesion force level and the second adhesion force level are both higher; and transferring the predetermined developer on the image-forming surface onto the image-carrying medium when the first adhesion force level is substantially higher than the second adhesion force level.
According to a third aspect of the current invention, a system for controlling relative adhesion force of predetermined developer and an image-forming surface with respect to a predetermined image-carrying medium, including a developer holding unit for holding the predetermined developer; a first adhesion force adjustment unit located near the developer holding unit for adjusting a first adhesion force level of the predetermined developer; a image-forming unit located near the developer holding unit having an image-forming surface and for selectively placing the toner on the image-forming surface; a second adhesion force adjustment unit located near the image-forming unit for adjusting a second adhesion force level of the image-forming surface; and whereby the predetermined developer is placed on the image-forming surface according to a desired image when the second adhesion force level is higher than the first adhesion force level, the predetermined developer on the image-forming surface is transferred onto the image-carrying medium when the first adhesion force level is higher than the second adhesion force level.
According to a fourth aspect of the current invention, a system for controlling relative adhesion force of predetermined developer and an image-forming surface with respect to a predetermined image-carrying medium, including: a developer holding unit for holding the predetermined developer; a first adhesion force adjustment unit located near the developer holding unit for adjusting a first adhesion force level of the predetermined developer; a image-forming unit located near the developer holding unit having an image-forming surface and for selectively placing the toner on the image-forming surface; a second adhesion force adjustment unit located near the image-forming unit for adjusting a second adhesion force level of the image-forming surface; and whereby the predetermined developer is placed on the image-forming surface according to a desired image when the first adhesion force level and the second adhesion force level are both higher, the predetermined developer on the image-forming surface is transferred onto the image-carrying medium when the first adhesion force level is higher than the second adhesion force level.
These and various other advantages and features of novelty which characterize the invention are pointed out with particularity in the claims annexed hereto and forming a part hereof However, for a better understanding of the invention, its advantages, and the objects obtained by its use, reference should be made to the drawings which form a further part hereof, and to the accompanying descriptive matter, in which there is illustrated and described a preferred embodiment of the invention.